Armytage was returned unopposed at York as the candidate of Lord Rockingham, whom he followed in Parliament. Two speeches by him are recorded: 10 Dec. 1762, against the peace preliminaries;
In the autumn of 1767 Armytage declared he would not stand at the general election, pleading ill health, and ‘not being able to bear London’.
Armytage continued to support Rockingham in Yorkshire politics; he helped to organize the petition of 1769, was one of the deputation who presented it to the King, and was chairman of the county meeting in 1770. He died 21 Jan. 1783.